1. Technical Field
The present invention relates to a bi-directional converter, and more particularly, to a method and a system of controlling a converter to prevent reverse powering occurring when a load of an output terminal of a converter is a low load.
2. Description of the Related Art
Recently, eco-friendly vehicles have been developed including hybrid vehicles that use both of the existing internal combustion engine and a battery as a power source. The hybrid vehicles may be driven by an electric motor upon starting and by the electric motor and an internal combustion engine upon driving the vehicle. In the typical driving system of the hybrid vehicles, an input side of a power converter is connected to a large-capacity high voltage battery and an output side thereof is connected to a motor or an auxiliary battery.
A DC-DC converter configured to convert a voltage for charging the auxiliary battery as a medium for power transfer is disposed between the high voltage battery and the auxiliary battery, often known as a low voltage DC-DC (LDC) converter. An LDC using a diode device and an LDC using switch devices (transistor, MOSFET, etc.) have been used as LDC's in the related art. Recently, the converter using the switch device may be boosted and bucked bi-directionally. The bi-directional converter using the switch device has different converter efficiency based on an on/off control of the switch device. Therefore, a method in the related art decreases an operation period of a switch device to increase an operation frequency of a transformer when an output capacity of a bi-directional converter is increased and increases the operation period of the switch device to decrease the operation frequency of the transformer when the output capacity thereof is decreased, thereby optimizing efficiency of the converter for a buck mode and a boost mode, respectively, while using one transformer. However, even by the above-mentioned method, the converter may still have the reduced efficiency and durability due to a reverse current flowing from the auxiliary battery to the high voltage battery side which may be generated by replacing the diode of the converter by the switch device.
The matters described as the related art have been provided merely for assisting in the understanding for the background of the present invention and should not be considered as corresponding to the related art known to those skilled in the art.